The present invention relates generally to the art of completing subterranean wells having lateral bores extending from parent bores thereof and, in a preferred embodiment thereof, more particularly provides apparatus for reentering the parent bores after the lateral bores have been cased and associated methods.
It is well known in the art of drilling subterranean wells to form a parent bore into the earth and then to form one or more bores extending laterally therefrom. Generally, the parent bore is first cased and cemented, and then a tool known as a whipstock is positioned in the parent bore casing. The whipstock is specially configured to deflect milling bits and drill bits in a desired The first wellbore is lined with a protective liner, which extends at least partially axially within the second wellbore. The first wellbore protective liner has an intersecting portion which extends laterally across the second wellbore proximate the intersecting portion of the first wellbore. The apparatus includes a milling guide and a cutting structure.
The milling guide has an axially elongated body portion which is receivable at least partially within the tubular structure, a generally axially and laterally extending guide profile formed on the body portion, and first and second opposite ends, the second opposite end being axially engageable with an anchor operatively disposed within the tubular structure.
The cutting structure is axially slidably disposed relative to the guide profile. Axial displacement of the cutting structure relative to the guide profile produces lateral displacement of the cutting structure relative to the milling guide.
A method of forming an opening through a tubular structure extending laterally across a wellbore to thereby provide access to the wellbore is provided as well. The method includes the steps of setting an anchoring structure within the tubular structure axially spaced apart from the wellbore, conveying an axially elongated milling guide axially into the tubular structure, the milling guide having a guide profile formed thereon, and the guide profile being capable of laterally outwardly displacing a cutting tool axially slidingly disposed thereon, axially engaging the milling guide with the anchoring structure, thereby axially aligning the milling guide with the anchoring structure, and axially slidingly displacing a cutting tool relative to the guide profile, thereby bringing the cutting tool into contact with the tubular structure.
The use of the disclosed apparatus and associated methods permits convenient and economical access to a parent wellbore where access to the parent wellbore has been cut off by a laterally extending liner.